02-08-2020, 09:40 AM
Here is a Pentode - Pentode in partial assembly. The green wire is the oscillator g2. I decided to remove that from pin 5 and connect g2 to anode to have triodised oscillator as all the mixer - oscillator circuits are for triode oscillators, The g1 and g2 of heptode and octode oscillators are really a triode; some even use two rods or plates as the g2 to feed electrons to the mixer stages.
I removed insulation from hook-up wire to colour code according to B7G pin. So yellow is the LO grid and blue is the RF grid. The two long wires are the B7G g2 (to oscillator anode) and final anode to IFT, the Pentode mixer anode. You actually have to ADD about 6pF to 8pF to the 1j24b pentode anode so you don't have to retune the IFT. It's a lower capacitance than most battery valves.
Here it is assembled, without a sleeve on the oscillator anode. You can see the g2 of the Pentode mixer (orange) and the g1 to RF grid (blue) and two 10 Ohm resistors to the violet filament + wires.
Anyway DON'T make a pentode - pentode. It's a triode - pentode that's wanted. So no green wire; that pin to HT has no connection, which is actually a second -f/screen grid to 0V pin on an 1R5/DK91.
Instead the oscillator g2 connects to the oscillator anode as well as the RF pentode mixer g2.
I removed insulation from hook-up wire to colour code according to B7G pin. So yellow is the LO grid and blue is the RF grid. The two long wires are the B7G g2 (to oscillator anode) and final anode to IFT, the Pentode mixer anode. You actually have to ADD about 6pF to 8pF to the 1j24b pentode anode so you don't have to retune the IFT. It's a lower capacitance than most battery valves.
Here it is assembled, without a sleeve on the oscillator anode. You can see the g2 of the Pentode mixer (orange) and the g1 to RF grid (blue) and two 10 Ohm resistors to the violet filament + wires.
Anyway DON'T make a pentode - pentode. It's a triode - pentode that's wanted. So no green wire; that pin to HT has no connection, which is actually a second -f/screen grid to 0V pin on an 1R5/DK91.
Instead the oscillator g2 connects to the oscillator anode as well as the RF pentode mixer g2.
